Mix sour cream with kefir and add soda, let stand for 5 minutes. Then beat the egg, sugar, vanillin, vegetable oil and salt, pour everything into kefir. Stir and add flour with lemon zest. Knead the dough.
You can’t knead the dough for a long time, grease your hands with oil so that it would not stick to your hands. Roll out the formation about 0.5 cm thick and cut the circles with a glass.
Cut the circles before reaching the middle several times.
Fry the crumpets in vegetable oil until golden brown on both sides, for about 2 minutes. Then let the fat drain on paper towels.
Kefir donuts are ready, sprinkle with powdered sugar and serve.